wT oes. Se 
on the Action of the Heart, ec. 447 
changes in the lungs, and I was therefore induced to doubt 
whether the abovementioned opinion respecting the source 
of animal heat is correct. No positive conclusions how- 
ever could be deduced from these experiments. If animal 
heat depends on the changes produced on the blood by the 
air in respiration, its being kept up to the natural standard, 
or otherwise, must depend on the quantity of air inspired, 
and on the quantity of blood passing through the lungs in a 
given space of time: in other words, it must be in proportion 
to the fullness and frequency of the pulse, and the fullness 
and frequency of the inspirations. It therefore became 
necessary to pay particular attention to these circumstances. 
Experiment 4.—The experiment was repeated on a dog 
of a small size, whose pulse was from 130 to 140 in a mi- 
nute, and whose respirations, as far as I could judge, were 
performed from 30 to 35 times in a minute. 
The temperature of the room was 63°. The heat in the 
rectum of the animal at the commencement of the experi- 
ment was 99°. ‘The artificial inspirations were made to 
correspond as nearly as possible to the natural inspirations 
both in fullness and frequency. 
At 20 minutes from the time of the dog being pithed, 
the heart acted 140 times in a minute with a3 much strength 
and regularity as before: the heat in the rectum had fallen 
to 964. 
At 40 minutes the pulse was still 140 in a minute: the 
heat in the rectum g@!, 
At 55 minutes the pulse was 112, and the heat in the 
rectum 90°. ‘ 
At one hour and ten minutes the pulse beat g0 in a mi- 
nute, and the heat in the rectum was 88°. 3 
At one hour and 25 minutes the pulse had’ sunk to 30, 
and the heat in the rectum was 85°. The bulb of the ther- 
mometer being placed in the bag of the pericardium, the 
mercury stood at 85°, but among the viscera of the abdo- 
men it rose to 874. 
_ During the experiment there were frequent and violent 
contractions.of the voluntary muscles, and an hour after 
the experiment was begun, there was an evacuation of 
fzeccs, ; 
_ Experiment 5.—The experiment was repeated on a rab- 
bit, whose respirations, as far as I could judge, were from 
30 to 40 in a minute, and whose pulse varied from 130 to 
140 in a minute. The temperature of the room was 57°. 
The heat in the rectum, at the commencement of the ex- 
periment, 
